Electronic Telegram No. 4069
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2015 D2 (PANSTARRS)
     R. Weryk and R. Wainscoat, Institute for Astronomy, University of Hawaii,
report the discovery of an apparent comet in four w-band exposures taken with
the 1.8-m Pan-STARRS1 telescope at Haleakala on Feb. 18.4 UT (discovery
observations tabulated below); the object shows an extended point-spread
function, with full-width-at-half-maximum of approximately 1".6, compared to
1".3 for adjacent stars.  Their follow-up observations on Feb. 19.4 show a
similar appearance (and similar extended point-spread function).

     2015 UT             R.A. (2000) Decl.       Mag.
     Feb. 18.38669    9 13 40.39   + 0 36 17.6   20.6
          18.39963    9 13 40.10   + 0 36 21.7   20.5
          18.41258    9 13 39.84   + 0 36 25.4   20.5
          18.42555    9 13 39.57   + 0 36 29.2   20.7

Wainscoat, Weryk, and M. Micheli obtained three 60-s r-band exposures of the
comet candidate using the 3.6-m Canada-France-Hawaii Telescope on Feb. 19.4
UT, with the telescope tracked non-sidereally using the predicted motion of
the object (queue observer P. Forshay); in each image, the object appears to
be extended with a faint, broad, low-surface-brightness tail extending for
approximately 5" to the west-southwest (magnitude given as 20.0-20.2).
After the object was posted on the MPC's PCCP webpage, H. Sato (Tokyo, Japan)
reported that ten stacked 60-s exposures taken with an iTelescope 0.51-m f/6.8
astrograph (+ luminance filter) at Siding Spring show a strongly condensed but
asymmetrical coma 15" in diameter of mag 19.2 as measured within a circular
aperture of radius 8".8.

     The available astrometry (including pre-discovery Pan-STARRS1 observations
from Jan. 19.5 UT, when the magnitudes was given as 20.6-21.2), the following
preliminary elliptical orbital elements by G. V. Williams, and an ephemeris
appear on MPEC 2015-D111.

     T = 2013 Oct.  6.5580 TT         Peri. = 292.5197
     e = 0.566707                     Node  = 163.0153  2000.0
     q = 5.609556 AU                  Incl. =  31.6404
       a = 12.946333 AU    n = 0.0211585    P =  46.6 years


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2015 CBAT
2015 February 28                 (CBET 4069)              Daniel W. E. Green